One piece optical assembly for low cost optical scanner

ABSTRACT

An optical scan module, for example for an optical scanner, includes an integrally molded plastics material member which defines not only the laser focusing lens, but also the laser focusing aperture and the collection mirror. In addition, the molded member may act to house and to locate both a semiconductor laser and a photodetector, thereby ensuring easy and accurate placement of those elements within the scanning assembly. The optical assembly may be in modular form, mounted onto a common printed circuit board with a beam scanner.

RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of U.S.application Ser. No. 08/727,944 filed Oct. 9, 1996.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The field of the invention relates to electro-optical readers orscanning systems, such as bar code symbol readers, and more particularlyto a scanning module for use in applications requiring particularlycompact scanners.

[0004] 2. Description of the Related Art

[0005] Electro-optical readers, such as bar code symbol readers, are nowvery common. Typically, a bar code symbol comprises one or more rows oflight and dark regions, typically in the form of rectangles. The widthsof the dark regions, i.e., the bars, and/or the widths of the lightregions, i.e., the spaces, between the bars indicate encoded informationto be read.

[0006] A bar code symbol reader illuminates the symbol and senses lightreflected from the coded regions to detect the widths and spacings ofthe coded regions and derive the encoded information. Bar code readingtype data input systems improve the efficiency and accuracy of datainput for a wide variety of applications. The ease of data input in suchsystems facilitates more frequent and detailed data input, for exampleto provide efficient inventories, tracking of work in progress, etc. Toachieve these advantages, however, users or employees must be willing toconsistently use the readers. The readers therefore must be easy andconvenient to operate.

[0007] A variety of scanning systems are known. One particularlyadvantageous type of reader is an optical scanner which scans a beam oflight, such as a laser beam, across the symbols. Laser scanner systemsand components of the type exemplified by U.S. Pat. Nos. 4,387,297 and4,760,248—which are owned by the assignee of the instant invention andare incorporated by reference herein—have generally been designed toread indicia having parts of different light reflectivity, i.e., barcode symbols, particularly of the Universal Product Code (UPC) type, ata certain working range or reading distance from a hand-held orstationary scanner.

[0008] A variety of mirror and motor configurations can be used to movethe beam in a desired scanning pattern. For example, U.S. Pat. No.4,251,798 discloses a rotating polygon having a planar mirror at eachside, each mirror tracing a scan line across the symbol. U.S. Pat. Nos.4,387,297 and 4,409,470 both employ a planar mirror which isrepetitively and reciprocally driven in alternate circumferentialdirections about a drive shaft on which the mirror is mounted. U.S. Pat.No. 4,816,660 discloses a multi-mirror construction composed of agenerally concave mirror portion and a generally planar mirror portion.The multi-mirror construction is repetitively reciprocally driven inalternative circumferential directions about a drive shaft on which themulti-mirror construction is mounted. All of the above-mentioned U.S.Patents are incorporated herein by reference.

[0009] In electro-optical scanners of the type discussed above, the“scan engine” including the laser source, the optics the mirrorstructure, the drive to oscillate the mirror structure, thephotodetector, and the associated signal processing and decodingcircuitry all add size and weight to the scanner. In applicationsinvolving protracted use, a large heavy hand-held scanner can produceuser fatigue. When use of the scanner produces fatigue or is in someother way inconvenient, the user is reluctant to operate the scanner.Any reluctance to consistently use the scanner defeats the datagathering purposes for which such bar code systems are intended. Also, aneed exists for compact scanners to fit into small compact devices, suchas notebooks.

[0010] Thus, an ongoing objective of bar code reader development is tominiaturize the reader as much as possible, and a need still exists tofurther reduce the size and weight of the scan engine and to provide aparticularly convenient to use scanner. The mass of the movingcomponents should be as low as possible to minimize the power requiredto produce the scanning movement.

[0011] It is also desirable to modularize the scan engine so that aparticular module can be used in a variety of different scanners. A needexists, however, to develop a particularly compact, lightweight modulewhich contains all the necessary scanner components.

SUMMARY OF THE INVENTION

[0012] Objects of the Invention

[0013] It is an object of the present invention to reduce the size andweight of components used to produce scanning motion of the light bean,and to collect the reflected light.

[0014] A related object is to develop an electro-optical scanning systemwhich is both smaller and lighter in weight.

[0015] It is yet a further object to produce a module which may bemanufactured conveniently, and at low cost. A related object is toprovide a module which may be assembled easily.

FEATURES OF THE INVENTION

[0016] According to the present invention there is provided an opticalscan module comprising:

[0017] (a) a light source for emitting a light beam;

[0018] (b) a scanning assembly for receiving said light beam and forgenerating therefrom a scanning beam directed to an indicia to be read;

[0019] (c) a photodetector; and

[0020] (d) a one-piece optical element including:

[0021] (i) a beam-shaping lens for receiving and shaping said light beamprior to transmission to said scanning assembly; and

[0022] (ii) a mirror-defining portion for locating a mirror surface,said mirror surface being arranged to receive reflected light from saidindicia and to direct it to said photodetector.

[0023] Preferably, the one-piece or integral optical element may bemolded from an optically transparent plastics material which isselectively coated to provide the collection mirror reflective surface.The molded member may also define mounting and/or location portions forthe light source/laser and/or the photodetector. The photodetectormounting portion may also be coated, preferably with the same materialthat is used to coat the collection mirror, so as to provide not onlyoptical but also electromagnetic shielding for the photodetector.

[0024] The molded member may include downwardly-extending “snaps”,allowing the member, along with the mounted laser and photodetector,easily to be secured to an underlying PCB.

[0025] Also on the same PCB may be mounted a beam scanning arrangementproviding either linear or two-dimensional scanning.

[0026] According to the invention there is further provided an opticalscan module comprising a mounting base defining a reference plane andhaving mounted thereon;

[0027] a) a light source for emitting a light beam;

[0028] b) a scanning assembly for receiving said light beam and forgenerating therefrom a scanning beam directed to an indicia to be readin which said module is arranged such that the scanning beam defines ascanning plane which is non-orthogonal to the reference plane.

[0029] Accordingly the module can be placed on a mother board withoutthe need of spacers to achieve a desired angle.

[0030] In another form the invention provides an optical scan modulecomprising a base defining a reference plane, a beam reflecting elementand a beam reflecting element drive, in which the beam reflectingelement is mounted relative to the base to be driven to oscillate in aplane angled to a plane orthogonal to the reference plane.

[0031] According to the invention there is further provided a small-sizeoptical scan module comprising a substantially rectangular module base,and mounted thereon a light source for emitting a light beam, a scanningassembly for receiving said light beam and for generating therefrom ascanning beam directed to an indicia to be read, a detector, and a onepiece optical element including a beam shaping lens for receiving andshaping said light beam prior to transmission to said scanning assemblyand a mirror defining portion for locating a mirror surface, said mirrorsurface being arranged to received retro-reflected light and to directit to said detector.

[0032] The invention further provides an optical scan module comprisinga light source for emitting a light beam, a first scanning assembly forreceiving said light beam and for generating therefrom a scanning beamin a first scanning plane; a second scanning assembly for receiving saidscanning beam from said first scanning assembly and for generating ascanning beam also scanning in a second plane non-parallel to the firstscanning plane; and a detector for detecting a returning beam in whichthe light source, the scanning assembly and the detector are provided ona single module base. Accordingly two dimensional scanning is achievedallowing customised scan patterns.

[0033] According to the invention there is further provided a scanningelement for an optical scanner, the scanning element including areflector for reflecting a scanning beam and a drive for driving thereflector in a scanning motion in which the reflector is mounted on atorsionally deformable element and is driven in a scanning motionthereon, and in which the torsionally deformable element is elongate,deformable about its elongate axis, and non-planar in cross sectionalshape perpendicular to its elongate axis, said cross sectional shapebeing selected to provide substantially uniform torsional deformationalong the elongate axis.

[0034] The invention also provides an optical reader comprising a readerhousing, and a reading beam generator, a reading beam detector and areading beam window mounted in the housing, the housing comprising abase, a handle and a head portion, including the reading window, mountedat one end of the handle, the handle being attached at its other end tothe base, in which the reader is free-standing on the base. An improvedergonomic including hands-free/free-standing and hand-held use is thusachieved.

[0035] The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.Further features of the invention are set out in the appendedindependent claims, and further preferred features are set out in thedependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a partially sectioned view of an optical assemblyaccording to the preferred embodiment of the invention;

[0037]FIG. 2a shows a side view of a gun-type scanner suitable for usewith the optical assembly of FIG. 1;

[0038]FIG. 2b is a front view of the scanner of FIG. 2a;

[0039]FIG. 2c is a plan view of the scanner of FIG. 2a;

[0040]FIG. 2d is an exemplary hand-held optical scanner, suitable foruse with the optical assembly of FIG. 1;

[0041]FIG. 2e is an exemplary hand-held combined computer terminal andoptical scanner, again suitable for use with the optical assembly ofFIG. 1;

[0042]FIG. 3 shows an optical assembly from which a scanning beam existsat a non-90° angle;

[0043]FIG. 4 is a flow chart showing operation of the scanner of FIGS.2a-2 c;

[0044]FIG. 5a shows a think flexible band drive of known type;

[0045]FIG. 5b shows an improved think flexible band;

[0046]FIG. 6 is an exploded view showing mounting of the thin flexibleband of FIG. 5b;

[0047]FIG. 7 shows the components set out in FIG. 6 in assembled form;

[0048]FIG. 8 shows an optical assembly in a housing in cut-away from;

[0049]FIG. 9 shows a 2D scan motion scanner assembly;

[0050]FIG. 10 is a schematic plan view corresponding to FIG. 9;

[0051]FIG. 11 shows an alternative scan assembly configuration;

[0052]FIG. 12 is an end view corresponding to FIG. 11;

[0053]FIG. 13a illustrates the scanning plane in a conventionalassembly;

[0054]FIG. 13b illustrates the scanning plane in an assembly of the typeshown in FIG. 11; and

[0055]FIG. 14 shows an alternative scan module housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056]FIG. 1 shows a low-cost optical assembly, according to thepreferred embodiment, for creating a scanning laser beam.

[0057] The optical assembly comprises two essentially separate portions,the “static optics” 10 and the scanner motor drive 12, both mounted to acommon printed circuit board (PCB) 14. Before the structure of theassembly is described in detail, it may be helpful to provide a briefoverview of the operation of the device. The light beam 16 from asemi-conductor laser 18 passes through a molded plastics lens 20 and isturned through 90° by total internal reflection from a prism 22. Afterexiting the prism, the beam passes through an aperture 24 in a collectormirror 26, and impinges onto an oscillating scanning mirror 28. Thisproduces a scanning outgoing light beam 30, which is directed toward anindicia (not shown) to be read.

[0058] Reflected light 32 from the indicia is first received by thescanning mirror 28, which directs it onto a concave surface 34 of thecollector mirror 36. This focuses the light via an aperture 36 and afilter 38 onto a photodetector 40. The photodetector output signal isthen passed on to suitable electronics within the PCB 14 by anelectrical coupling 42.

[0059] The scanning mirror 28 is mounted at 44 for oscillation about anaxis, this being achieved by virtue of the interaction between apermanent magnet 46 and a driven electromagnetic coil 48. A suitabledriving signal is applied to the coil, via the PCB 14 and coilelectrical contact 50.

[0060] The scanner motor drive 12 shown in FIG. 1 is exemplary, and maybe replaced with any type of mechanism for effecting a scanning motionof the beam in one or two dimensions. For example, the scanner motordrive could comprise any of the configurations disclosed in U.S. Pat.Nos. 5,581,067 and 5,367,151, all of which are incorporated byreference. In this way, the static optics assembly 10 may be used as acomponent in a variety of scanner designs.

[0061] The optical assembly shown in FIG. 1 may be incorporated withinany type of fixed or portable optical scanner, for example the scan-typescanner of FIGS. 2a-2 c the hand-held scanner shown in FIG. 2d or thehand-held computer terminal/scanner shown in FIG. 2e.

[0062] Referring to FIGS. 2a to 2 c a hand-held, gun-type scanner ofergonomic design is shown. The scanner includes a scanner bodydesignated generated 100 including a handle portion 102 and a headportion 104. The handle portion 102 is configured to be held upright inthe user's palm and has a forward portion including a trigger 106positioned preferably to be operable by the user's forefinger. The headportion 104 is provided at the top of the handle portion 102 andincludes a front face including a scanning window 108 and a bulbous rearportion extending rearwardly from the handle 102 to rest on or above theuser's hand in use.

[0063] The scanner 100 is pivotably fixed to a base portion 110 about apivot axis 112 provided at the lower end of the handle 102. The baseincludes a flat bottom face 114 and extends outwardly from the handleportion both forward and rear and to the sides such that the assembly asa whole can be placed freestanding stably on a supporting surface. Thescanner 100 is arranged to pivot on the base 110 in the forward/backwarddirection. The base 100 provides an interface between the scanner 100and a host (not shown) by a cable 116. The cable 116 can simply carrypower or can also include a data path either for control information tobe passed to the scanner or for data read to be downloaded to the hostfrom the scanner 100.

[0064] The base 110 includes on its underside 114 a pressure switch ofany suitable known type (not shown) release of which indicates to aprocessor in the scanner that the scanner is being operated in hand-heldmode. Accordingly the scanner switches to triggered mode indicating thatreading will only take place when trigger 106 is activated.

[0065] The control system is illustrated in more detail in the flowchart of FIG. 4. It will be seen that a continuous loop is maintained bya suitable controller establishing whether or not the pressure switch isactivated (step 150). If the pressure switch is deactivated thentriggered (hand-held) mode is entered (step 152); further discussion ofrelevant features may be found in U.S. Pat No. 5,151,581, incorporatedherein by reference.

[0066] In the alternative mode, where the pressure switch is activated,continuous scanning (hand free) mode 154 is entered. In this mode apresentation scan pattern is always activated allowing all items to passin front of the scanner to be scanned. This can be used for example at aretail sales point such as a check-out stand. Accordingly thearrangement allows dual mode operation.

[0067] The scanner is preferably an omni-direction scanner but thegun-type configuration provides the benefits of a conventionalone-dimensional scanner. In addition the adjustable angle provided bythe incorporation of a pivot axis 112 allows the scanner as a whole tobe positioned at any desired pivot angle for ease of reading and alsoallows the base to be angled to a comfortable position when in hand-heldmode.

[0068] The main body 100 and base 110 are preferably modular such thatone or other components can be changed at minimum expense to arrive at,for example, a cordless embodiment. Optionally a mode button 118 isadditionally provided on the upper face of the head 104 (see FIG. 2c)allowing the user to select a scanning pattern of any desired type forexample based on the bar code symbols or other indicia to be read, orthe scanning conditions. In addition indicator lights such as LED's areprovided at 120 which can indicate, for example, the mode of operationof the scanner, whether it is in hands-free or hand-held mode, and soforth.

[0069] Referring now to FIG. 2d, reference numeral 210 generallyidentifies a hand-held scanner in an alternative embodiment. The scannermay alternatively be gun-shaped, or any suitable configuration may beused. The scanner is manually-operable for example by a trigger (notshown). As known from the above-identified patents and applicationsincorporated by reference herein, a light source component,typically butnot necessarily a laser, is mounted inside the scanner shown at block210. The light source emits a light beam along a transmission path whichextends outwardly through a window 218 that faces indicia, e.g. bar codesymbols, to be read. Also mounted within the block 210 is aphotodetector component, e.g. a photodiode, having a field of view, andoperative for collecting reflected light returning through the window214 along a path from the symbol.

[0070] The optical assembly of FIG. 1 is mounted within or as part ofthe block 210.

[0071] In whichever scanner type the arrangement is provided, operationis generally the same. The photodetector generates an electrical analogsignal indicative of the variable intensity of the reflected light. Thisanalog signal is converted into a digital signal by an analog-to-digitalconverter circuit. This digital signal is decoded by a decode module222. The decode module 222 decodes the digital signal into datadescriptive of the symbol. An external host device 224, usually acomputer, serves mainly as a data storage in which the data generated bythe decode module 222 is stored for subsequent processing.

[0072] The block 210 and decoder 222 are mounted on a PCB 214.

[0073] In operation, each time a user wishes to have a symbol read, theuser aims the scanner at the symbol and pulls the trigger or otherwiseinitiates reading of the symbol. The trigger is an electrical switchthat actuates the drive means. The symbol is repetitively scanned aplurality of times per second, e.g. more than 100 times per second. Assoon as the symbol has been successfully decoded and read, the scanningaction is automatically terminated, thereby enabling the scanner to bedirected to the next symbol to be read in its respective turn.

[0074] In addition, the head need not be a portable hand-held type asfixedly mounted heads are also contemplated in this invention.Furthermore, the heads may have manually operated triggers, or may becontinuously operated by direct connection to an electrical source.

[0075] The oscillations need only last a second or so, since themultiple oscillations, rather than time, increase the probability ofgetting a successful decode for a symbol, even a poorly printed one. Theresonating reflector has a predetermined, predictable, known, generallyuniform, angular speed for increased system reliability.

[0076] Turning now to FIG. 2e, there is shown an alternative hand-heldoptical scanner including additional features, this time taking the formof a scanning terminal 326. The terminal comprises a hand-held case 328having a data display screen 30 and a data input keypad 332. The opticalassembly of FIG. 1, within the case 328, produces a scanning light beamwhich extends outwardly through a window 334 which faces the indicia tobe read. Light reflected from the indicia passes back through the window334 and impinges on the photodetector component, for example aphotodiode, which creates a returning light output signal. Theinformation content within that signal may be stored in an on-boardmemory (not shown) or may be downloaded to a remote computer via a dataport 336. Alternatively, the information may be transmitted via a radiofrequency signal produced by an on-board radio transmitter/receiver 338.

[0077] In one embodiment the motor drive used to obtain scanning actionis preferably a “taut band element” drive. This type of drive is fullydescribed in, inter alia, U.S. Pat. Nos. 5,614,706 and 5,665,954 whichare commonly assigned herewith and incorporated herein by reference. Inessence, the arrangement includes an optical element such as alightweight mirror mounted on a thin flexible strip (the “taut band”)mounted across an electromagnetic coil. A permanent magnet is attachedto the optical element which interacts with a varying magnetic fieldcreated when an AC signal is applied to the coil to cause repetitivetorsional motion in the flexible strip. As a result the optical elementoscillates providing scanning motion.

[0078]FIG. 5a shows a taut band element drive of known type in moredetail. In particular coil 70, flexible strip 72, mirror 74 andpermanent magnet 76 can be seen. The flexible strip 72 can be heldagainst the coil 70 for example by a holding annulus 78. An AC voltageapplied to the coil is represented schematically at 80 and causestorsional oscillation represented schematically by arrow 82. It will beapparent that this arrangement can replace the arrangement showngenerally in FIG. 1 as mirror 28 and drive arrangement 44, 46, 48 in amanner apparent to the skilled reader.

[0079] In a further embodiment shown in FIG. 5b the flexible strip 72 isreplaced by an elongate element 84 which is V-shaped in cross-sectionperpendicular to its elongate axis on which is mounted the mirror 74 andpermanent magnet element 76. The V-shaped element 84 extends across acoil or is otherwise appropriately mounted in the same manner asprevious thin flexible element 72 and the permanent magnet 76 interactswith the AC magnetic field resulting in torsional deflection representedby arrow 86. The V-shaped cross section of the band increases itsstiffness and in particular ensures that the torsional deflection isuniform or substantially uniform over the length of the band, the mirror74 being mounted on the apex of the “V”. It will be appreciated thatalternative configurations for the band cross section can becontemplated such as X shaped, I or H shaped, W shaped as long as therequirements of torsional deflection and uniformity of that torsionaldeflection along the length of the band are maintained.

[0080]FIG. 6 shows in exploded form a practical mode of mounting theV-shaped element 84 of FIG. 5b. Coil 70 is mounted on an E-configurationcore 71 a including a central arm 71 b which is received in the centralrecess of the coil 70 and outer arms 71 c and 71 d which extend eitherside of the coil and above it. A mounting plate 75 a is received on theouter arm 71 c, 71 d of the E-core and extends above and across the coil70. The mounting plate 75 a includes a central aperture 75 b definingthe space across which the V-shaped element 84 extends. The V-shapedelement 84 includes limbs 84 a extending either side of its longitudinalaxis symmetrically at either end and the centre and is mounted on themounting plate 75 a across the aperture 75 b in any suitable manner, forexample by securing the end limbs 84 a to the upper face of the mountingplace 75 a. Cooperatingly configured V-shaped connecting elements 85 aresecured to the V-shaped element 84 and generally aligned with the limbs84 a and the mirror 74 is mounted on the connecting elements 85 at theapex of the V-shaped element. Depending from the mirror 74 is a yoke 73also substantially of V-shaped but straddling the V-shaped element 84,having its outer ends 73 a, 73 b attached to the rear of the mirror 74.The yoke 73 has a central portion which extends away from the mirror 74and has lateral tabs 73 a, 73 d. The lateral tabs 73 a and 73 d are inregister with the central limbs 84 a, 84 b of the V-shaped element andare attached thereto. The permanent magnet 76 is attached to theunderside of the central portion of the yoke 73 for example to theunderside of the tabs 73 a and 73 d. Accordingly the yoke 73 straddlesthe V-shaped element 84 such that the permanent magnet projects over orthrough the aperture 75 b in the mounting plate 75 a allowing optimummagnetic coupling with the coil 70. When an AC current is applied to thecoil 70 the permanent magnet 76 oscillates which in turn gives rise totorsional flexing of the-V-shaped element 84 and oscillation of themirror 74. The assembled arrangement is shown in FIG. 7.

[0081] An assembled module incorporating the arrangement of FIG. 7 isshown in FIG. 8 in which it will be seen that a substantially cuboidalhousing is incorporated. The direction of angular motion of the mirroris depicted by arrow A.

[0082] Alternatively the type of motor drive used to oscillate the scanmirror can be a “mylar motor” for example of the unbalanced type asdiscussed below in relation to FIGS. 11-12 according to which the mirroris mounted to a mylar leaf spring which flexes back and forth as thepermanent magnet is driven by the AC coil imparting oscillating motion.Yet a further alternative is a micro machine mirror as discussed in theintroduction in relation to U.S. Pat. Nos. 4,387,297 and 4,409,470according to which the mirror is driven back and forth directly by asuitable drive motor, preferably of very small dimension. Yet a furtheralternative is to use a mirror of known rotating polygon type asdiscussed in the introduction in relation ot U.S. Pat. No. 4,251,798according to which the mirror comprises a solid body having a pluralityof face angled to one another. As the body rotates the beam is scannedby successive rotating faces of the polygon body. In one embodiment themylar motor can be used in an arrangement for one dimensional scanningwhilst a V-shaped taut band element (described above) can be used fortwo dimensional scanning also as discussed in more detail below.

[0083] Turning now to the static optics assembly 10 shown in FIG. 1, itwill be noted that the laser focusing lens 20, the laser aperture 24 andthe collection mirror 26 are all defined by a single molded plasticsmaterial member, shown in cross-hatching and indicated generally by thereference numeral 52. The molded member 52 further acts to house and tolocate the laser 18, the filter 38 and the photodetector 40.

[0084] The preferred laser 18 is a semiconductor laser, and preferablyan SMD (“surface mounted device”) photodiode. This eliminates the needfor photodiode standoffs and hand-soldering or sockets, as are used onprior art scanners. Typically, the laser will be a standard packagededge-emitting laser. For minimum cost, the laser focusing is notadjustable, and the laser is simply installed with its mounting flangein contact with a shoulder molded as part of the molded member. Thiswill position the laser accurately enough with respect to the moldedfocusing lens 20 to provide adequate performance within an inexpensivescanner. The fact that the focusing lens is molded as part of the samecomponent as the shoulder 54 minimises tolerance build-ups that couldotherwise cause improper focusing.

[0085] The laser is held in place within the molded member 52 by meansof UV-curing cement. Since the plastics material of the molded member istransparent to UV light, the cement may be cured by shining UV lightthrough the member into the cavity within which the laser is positioned.Cement may be applied to the laser 18, or to the molded member 52, withthe laser then being pushed into the cavity until it abuts thepositioning shoulder 54. The assembly may then be exposed to ultravioletlight for a few seconds, so curing the cement. If desired for higherperformance, this method of retaining the laser also allows for afocusing adjustment to be made. In this case, the laser is graduallyslid into the cavity while the output beam is being monitored. Whencorrect focus is achieved, the assembly is exposed to UV light, thuscuring the cement and locking the assembly into place.

[0086] In the unadjusted assembly, it may be possible to eliminate thecement by spring-loading the laser up against the positioning shoulder54, for example by means of a rubber or foam washer 56 between the PCB14 and the bottom of the laser 18.

[0087] As shown in the drawing, the laser 18 has dowardly-extendingelectrical leads 58 which are simply installed directly into the PCB 14.This eliminates hand-soldering, but soldering could be used if desired.

[0088] The fact that the leads extend downwardly into the circuit boardmeans that in a conventional laser, the beam will be directly upwardlyperpendicular to the board. The prism 22, previously described, ismolded into the top of the molded member 52 to direct the vertical laserbeam through the aperture 24 in the collector mirror 26 towards thescanning mirror 28. The prism 22 uses total internal reflection toreflect the laser beam, so it is not necessary to coat the upper surfacewith a reflective coating.

[0089] To provide for further focusing of the laser beam, should it bedesired, it would also be possible to shape the exit surface 60 of theprism.

[0090] It is desirable that, somewhere along its path, the laser beamshould pass through a beam stop. The aperture 24 in the collector mirror26 may serve this purpose. Alternatively, the lens 20 or the reflectingor exit surface of the prism 22 could provide the beam stop.

[0091] In fact it is preferred to keep the aperture 24 as small aspossible which improves the collection capability of the collectormirror 26. For example the aperture 24 may be in the region of 0.5 mm indiameter. This provides an additional advantage as the resultingdiffraction pattern gives rise to a light distribution following aBessel function which is particularly well adapted for scanning indicia.

[0092] The molded member 52 needs to be secured to the circuit board 14,and to that end snaps 62, 64 are provided. These automatically latchonto the circuit board when the component is installed. Alternatively,posts on the lower side of the molded member may protrude through theboard to be heat-staked onto the bottom of the board. Ultrasonic stakingcould also be used.

[0093] The collector mirror 26 is coated with a reflective coating sothat light impinging upon it will be reflected downwardly toward thephotodetector 40. This coating may also cover that part 62 of the moldedmember that serves as a housing for the photodiode. This will render theoptics assembly opaque in that area to prevent any light from reachingthe photodiode except via the aperture 36 and the filter 38.

[0094] This reflective coating may also serve another function.Typically, the coating will be a thin film of metal such as gold,aluminium or chrome. These films are electrically conductive.Accordingly, the film also acts as an electromagnetic interferenceshield for the photodiode 40. The use of a surface coating to protectthe photodiode enables the usual EMI shield to be dispensed with,thereby eliminating both the cost of a separate shield and the labor tohave it installed within the assembly.

[0095] The coating is electrically grounded by extending a projection 66of the molded member into a small socket 68 in the PCB. Alternatively,the projection 66 could be press-fitted into a plated through-hole inthe board.

[0096] The housing portion 62 of the molded member 52 not only acts tohold the optical filter 38 in place on top of the photodiode 40, butalso entirely surrounds the photodiode, thereby preventing stray lightfrom reaching it. The aperture 36 in the housing may be small to limitthe field of view of the detector, maximising ambient light immunity.The aperture needs to be accurately located with respect to thecollector mirror 26, to allow the use of a minimum-sized field of view.Accurate relative positions of the aperture and the collector mirror areeasily achieved since they are molded as a single part.

[0097] An alternative arrangement is shown in FIG. 3. In certaincircumstances it is desired to provide an arrangement in which the beam30 leaves the optical assembly at an angle other than 90° to thevertical (relative to the PCB 14). For example there may be instances inwhich the mounting requirements mean that the PCB 14 is mounted at anon-orthogonal position. In previous arrangements it has been necessaryto overcome this problem by introducing additional spacers when mountingthe PCB 14 such that the beam 30 leaves at the desired angle. Thisproblem is solved in the arrangement according to FIG. 3 by adjustingthe angle by which the beam exits the optical assembly to compensate forthe mounting angle and remove the need to mount the PCB including aspacer. In the arrangement shown this is achieved by altering the angleof the scanning mirror assembly 28, which is of particular benefit as noadjustment of the laser mounting would be required. It will beappreciated that the remaining optics may also require adjustment tofurther compensate which adjustments can be easily achieved by theperson skilled in the art.

[0098] The angle involved is dependent on the particular consumerrequirements but may be in the region of 45-90° to the PC board, morepreferably in the range of 60-70° and most preferably 65° to the PCB.

[0099]FIGS. 11 and 12 show an alternative optical assembly and motordrive embodiment to FIG. 3 according to an embodiment of the invention.The arrangement is mounted on a single base board 500 and includes alaser assembly 502 of suitable type for example of the type discussedabove. A beam from the laser assembly 502 passes through an aperture 504in a collector mirror 506 and is reflected by a scanning mirror 508. Thereturning beam is retroreflected onto the collector mirror 506 anddirected to a detector of suitable known type 510. Turning now to thedrive assembly for the scanning mirror 508 in more detail the mirror ismounted in conjunction with a permanent magnet 512 which interacts witha magnetic field provided by an AC current driven coil 514 to oscillatethe mirror. The mirror is mounted relative to the base 500 via anattachment element 501 which is connected to the mirror by two mylarsprings 518, 520. Although the mirror is mounted parallel to the basethe attachment element 516 is mounted at 25° to the horizontal base andthe mylar springs which extend perpendicular to the attachment strip 516are hence at 25° to the vertical. Accordingly a scanning plane isdefined at 25° to the vertical as discussed in more detail below. Itwill be appreciated, of course, that any appropriate angle can beselected. The scan angle is then defined by the amplitude of motion ofthe mirror and is preferably selected to be 50°. The mirror is of theunbalanced type, that is, no counterweights are provided against themirror mass.

[0100] It will be seen that the mirror 508 is angled relative to thevertical to direct the scanning beam out of the upper face of theassembly. As with FIG. 1 although the mirror 508 is represented in FIG.11 as being also angled out of a plane orthogonal with a plane of thepaper, this is merely a drawing representation to render the figure,clearer. It will be seen that the attachment element 516 includes limbs522 and 524 extending either side of the mylar springs 518, 520. Theselimbs are positioned within shaped recesses in side blocks 526, 528allowing a certain amount of clearance for the limbs which providesadequate space for the desired scanning angle to be achieved whilstproviding stops to limit the amount of oscillation of the mirror shoulda shock be imparted to the unit for example by dropping it.

[0101] Accordingly a beam emitted by the laser assembly 502 incident onthe mirror 508 is swept through an angle of 50° by the scanning mirror,however the plane of sweep of the beam (the scan plane) is not at 90° tothe base 500 but is at an angle constrained by the direction in whichthe magnet is driven to oscillate i.e. the axis of flexing of the mylarsprings. This can be best be understood with reference to FIGS. 13a and13 b. In FIG. 13a the laser beam 30 enters in the Y direction. Themirror and drive assembly are not shown but in FIG. 13a the normalmirror configuration is assumed that is the mirror is angled at 45° tothe X Z plane and is mounted to oscillate about the X direction. As aresult a scan plane 530 is established in the Y Z plane. However in FIG.13b the mirror and mirror drive are mounted as discussed in relation toFIGS. 11 and 12. It will be seen, therefore, that the scan line isobtained in a plane 532 at 25° to the Y Z plane. Again, any desired scanplane angle or scanning angle can be selected.

[0102] Accordingly a non-90° output angle of the beam as discussed inrelation to FIG. 3 is achieved in a different manner.

[0103]FIG. 9 shows a second preferred embodiment in whichtwo-dimensional scanning motion is achieved by using two mirrors eachoscillating in an orthogonal claim. Multi-pattern scanners can beachieved by using two reflector X-Y motion as described in U.S. Pat.Nos. 5,581,070, 5,637,856 and 5,614,706 all of which are incorporatedherein by reference. Preferably the two reflectors are driven by a thinflexible element-type drive of the type shown in FIG. 5a or FIG. 7. Inparticular the optical module 10 emits a beam 30 through aperture 24 incollector 34 which is oscillated in a first direction for example the Xdirection by a first oscillating mirror 28 a mounted on a first V-shapedelement 84 and is then oscillated in a second direction for example theY direction by a second mirror 28 b mounted on a V-shaped band 84. As aresult any desired scanning pattern can be achieved at the target asrepresented schematically by pattern 11. All of the elements arepreferably provided in a single module as can be seen from the base layout depicted in FIG. 10. In particular laser 18 emits an outgoing beam30 through an aperture 34 in collector mirror 26. The beam is oscillatedin the X direction by mirror 28 a and in the Y direction by mirror 28 bgiving rise to a scanning pattern shown schematically at 11. Thereturning beam 32 returns along the reflection path and is directed ontothe detector 40 by the collector mirror 26. It will of course beappreciated that the arrangement is preferably used in conjunction withthe optical assembly shown in FIG. 1 and the exact positioning andorientation of the parts will be apparent to the skilled reader.

[0104]FIG. 14 shows an alternative scan engine form-factor and ergonomichousing variation for incorporation of the scanner described herein orany other suitably dimensioned scanner. In particular the scanner isincorporated into a pen-type housing 600 having a scanning window 602.The pen-type housing 600 is preferably elongate having broad front andrear faces 604, 606 and narrow side faces. The scanning window ispreferably provided at the upper end of broad face 604, at the oppositeend to the pen “nib” 612 . Scanning can be triggered by one or moretriggers 608, 610 provided for example on the side or front face of thepen housing 600. The pen nib 612 can either be a conventional pen or anelectronic pen. Because of the broad faces the arrangement easily housesa scanner module of the type described herein. In addition thepositioning of the window 602 allows ergonomic scanning and thepositioning of a plurality of triggers allows left or right handed usersto use the scanner with ease. It will be seen that the broad rear face606 of the housing 600 contacts the user's palm in reading mode forcomfort and ease of use whilst in the writing mode the narrow side facecontacts the user's palm, so that the arrangement can be used normallyas a pen.

[0105] It will be understood that each of the features described above,or two or more together, may find a useful application in other types ofscanners and bar code readers differing from the types described above.

[0106] While the invention has been illustrated and described asembodied in a scan module for an electro-optical scanner, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit and scope of the present invention. In particular it will berecognised that features described in relation to one embodiment can beincorporated into other embodiments as appropriate in a manner that willbe apparent to the skilled reader.

[0107] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic or specific aspects of thisinvention and, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.
 1. An optical scan module comprising:(a) a light source for emitting a light beam; (b) a scanning assemblyfor receiving said light beam and for generating therefrom a scanningbeam directed to an indicia to be read; (c) a photodetector; and (d) aone-piece optical element including: (i) a beam-shaping lens forreceiving and shaping said light beam prior to transmission to saidscanning assembly; and (ii) a mirror-defining portion for locating amirror surface, said mirror surface being arranged to receive reflectedlight from said indicia and to direct it to said photodetector.
 2. Anoptical scan module according to claim 1 wherein said mirror surfacecomprises a coating on said one-piece optical element.
 3. An opticalscan module according to claim 1 wherein said one-piece optical elementdefines a beam stop for said light beam.
 4. An optical scan moduleaccording to claim 3 wherein said beam stop is defined by an aperture insaid mirror-defining portion.
 5. An optical scan module according toclaim 3 wherein said beam stop is defined by said beam-shaping lens. 6.An optical scan module according to claim 1 wherein said one-pieceoptical element includes an integral beam-folding prism.
 7. An opticalscan module according to claim 6 wherein said beam-folding prism isarranged to fold said beam by total internal reflection.
 8. An opticalscan module according to claim 6 wherein said beam-folding prism definesa beam stop for said light beam.
 9. An optical scan module according toclaim 1 wherein said one-piece optical element includes alight-source-locating portion.
 10. An optical scan module according toclaim 9 wherein said light source locating portion comprises a shoulderon the one-piece optical element which abuts said light source.
 11. Anoptical scan module according to claim 1 wherein said one-piece opticalelement includes a light-source-housing portion.
 12. An optical scanmodule according to claim 1 wherein said one-piece optical elementincludes a photodetector-locating portion.
 13. An optical scan moduleaccording to claim 1 wherein said one-piece optical element includes aphotodetector housing portion.
 14. An optical scan module according toclaim 13 wherein said photodetector housing portion comprises a locatingcavity within the integral optical element.
 15. An optical scan moduleaccording to claim 14 wherein said photodetector housing portion iscoated with an electromagnetic shielding material.
 16. An optical scanmodule according to claim 13 wherein the electromagnetic shieldingmaterial further provides optical shielding.
 17. An optical scan moduleaccording to claim 2 wherein the one-piece optical element includes aphotodetector housing portion, said photodetector housing portion alsobeing coated with said coating to provide electromagnetic shielding forsaid photodetector.
 18. An optical scan module according to claim 13wherein said photodetector housing portion defines an aperture to limitthe photodetector's field of view.
 19. An optical scan module accordingto claim 1 wherein said one-piece optical element includes mountingportions for mounting said optical scan module to a printed circuitboard.
 20. An optical scan module according to claim 19 wherein saidhousing portions comprise flexible snaps.
 21. An optical scan moduleaccording to claim 1 wherein said one-piece optical element is molded ofa plastics material.
 22. An optical scan module according to claim 1wherein said mirror surface is arranged to receive said reflected lightvia said scanning assembly.
 23. An optical scan module according toclaim 1 wherein said optical scan module comprises a mounting basedefining a reference plane and the scan module is arranged such that alight beam is emitted from the scan module at a non-orthogonal angle tothe reference plane.
 24. An optical scan module according to claim 23 inwhich the mirror defining portion is positioned to provide emission of alight beam at said non-orthogonal angle.
 25. An optical scan modulecomprising a mounting base defining a reference plane and having mountedthereon; a) a light source for emitting a light beam; b) a scanningassembly for receiving said light beam and for generating therefrom ascanning beam directed to an indicia to be read in which said module isarranged such that the scanning beam defines a scanning plane which isnon-orthogonal to the reference plane.
 26. An optical scan module asclaimed in claim 25 in which the scanning assembly is mounted at anangle such that the scanning plane is non-orthogonal to said referenceplane.
 27. An optical scan module as claimed in claim 25 in which thescanning plane is at an angle to the reference plane in the range of45-90°, more preferably 60-70° and most preferably 65°.
 28. An opticalscan module according to claim 4 wherein said aperture is of relativelysmall dimension compared to said mirror-defining portion.
 29. An opticalscan module according to claim 28 in which said aperture is of suitabledimension to cause diffraction of the beam.
 30. An optical scan moduleas claimed in claim 28 in which the aperture diameter is approximately0.5 mm.
 31. An optical scan module comprising a base defining areference plane, a beam reflecting element and a beam reflecting elementdrive, in which the beam reflecting element is mounted relative to thebase to be driven to oscillate in a plane angled to a plane orthogonalto the reference plane.
 32. A module as claimed in claim 31 in which thereflecting element is mounted on a resilient deformable element disposedon the base to deform about an axis non-parallel to the reference plane.33. A module as claimed in claim 32 in which the reflecting element ismounted on a flexible leaf spring having a flexing axis non-parallel tothe reference plane.
 34. A small-size optical scan module comprising asubstantially rectangular module base, and mounted thereon a lightsource for emitting a light beam, a scanning assembly for receiving saidlight beam and for generating therefrom a scanning beam directed to anindicia to be read, a detector, and a one piece optical elementincluding a beam shaping lens for receiving and shaping said light beamprior to transmission to said scanning assembly and a mirror definingportion for locating a mirror surface, said mirror surface beingarranged to received retro-reflected light and to direct it to saiddetector.
 35. A module as claimed in claim 34 in which the scanningassembly includes a reflecting element moveably mounted relative to thebase and means for moving the reflecting element, in which thereflecting element is mounted via a resilient coupling.
 36. A module asclaimed in claim 35 in which the resilient coupling comprises a leafspring.
 37. A module as claimed in claim 35 in which the resilientcoupling comprises a torsionally deformable elongate element.
 38. Amodule as claimed in claim 35 in which the reflecting element ismoveable to oscillate at high speed.
 39. An optical scan modulecomprising a light source for emitting a light beam, a first scanningassembly for receiving said light beam and for generating therefrom ascanning beam in a first scanning plane; a second scanning assembly forreceiving said scanning beam from said first scanning assembly and forgenerating a scanning beam also scanning in a second plane non-parallelto the first scanning plane; and a detector for detecting a returningbeam in which the light source, the scanning assembly and the detectorare provided on a single module base.
 40. A module as claimed in claim39 further including a one piece optical element including abeam-shaping lens for receiving and shaping said light beam prior totransmission to said scanning assembly; and a mirror defining portionfor locating a mirror surface said mirror surface being arranged toreceive retro-reflected light and to direct it to said detector.
 41. Amodule as claimed in claim 39 in which each reflector element is mountedon a torsionally deformable element and driven to oscillate on saidelement.
 42. A scanning element for an optical scanner, the scanningelement including a reflector for reflecting a scanning beam and a drivefor driving the reflector in a scanning motion in which the reflector ismounted on a torsionally deformable element and is driven in a scanningmotion thereon, and in which the torsionally deformable element iselongate, deformable about its elongate axis, and non-planar in crosssectional shape perpendicular to its elongate axis, said cross sectionalshape being selected to provide substantially uniform torsionaldeformation along the elongate axis.
 43. An element as claimed in claim42 in which the torsionally deformable element has, as its crosssectional shape one of the group of shapes: V shaped, X shaped, Ishaped, H shaped, W shaped.
 44. An element as claimed in claim 43 inwhich the torsionally deformable element is V-shaped in cross sectionalshape.
 45. An element as claimed in claim 44 in which the mirror ismounted at the apex of the V-shaped torsionally deformable element. 46.An optical reader comprising a reader housing, and a reading beamgenerator, a reading beam detector and a reading beam window mounted inthe housing, the housing comprising a base, a handle and a head portion,including the reading window, mounted at one end of the handle, thehandle being attached at its other end to the base, in which the readeris free-standing on the base.
 47. A reader as claimed in claim 46 inwhich the handle is pivotably mounted on the base.
 48. A reader asclaimed in claim 46 in which the base includes a mode detector to detectwhether the reader is in free-standing mode or hand-held mode.
 49. Areader as claimed in claim 48 in which the mode detector comprises apressure switch on the underside of the base.
 50. A reader as claimed inclaim 48 in which operation of the reader is varied according to themode detected.
 51. A reader as claimed in claim 50 in which, ifhand-held mode is detected a reading beam is generated only when anactuator is actuated.
 52. A reader as claimed in claim 50 in which iffree-standing/hands-free mode is detected a reading beam is generatedcontinuously allowing hands-free operation.
 53. A reader as claimed inclaim 46 comprising a flying spot optical scanner.
 54. A reader asclaimed in claim 46 comprising a field of view scanner.
 55. An opticalscan module as claimed in claim 1 further comprising a pen-type modulehousing having a rectangular cross section perpendicular to its longaxis defining opposing broad elongate faces and opposing narrow elongatefaces, having as one end a pen end and further including a scanningwindow provided on a broad elongate face substantially at the other end.